Eighteen-year-old Mariah Durojaiye is always on the prowl for the most anticipated, trendiest sneakers. She's just one of a growing number of devoted sneaker buffs who will comb the Internet, camp out in the wee hours and pay top dollar for the most sought-after athletic shoes.

"It is like part of my culture. All of our friends are really big 'sneakerheads.' It is who we are," said Durojaiye. "There are so many different trends and styles and colors. It is a fun way to be fashionable."

Durojaiye, who enters college in September, buys about five to 10 pairs of designer sneakers each year. She said she uses her "mom's finances" or gets them as gifts for her birthday and holidays.

Her mother, Debbie Montford, hopes her daughter finds a job soon to help pay for her sneaker habit.

"Even the kids I work with have every pair of sneakers that come out," said Montford, a special education teacher. "Where do the people get the money to pay for these? I have a pair of Skechers. I love Skechers."

While a pair of Skechers typically costs between $49 and $110, some of the most sought-after sneakers start at prices above that range and can cost as much as $300. But the truly hot sneakers sell out fast, forcing fans to buy them in secondary markets where they can cost hundreds of dollars above their retail price.

Sneaker sales have been a healthy part of the retail economy, and the online portion is growing fast. Market researcher NPD Group estimated the total ecommerce athletic footwear market in the U.S. was worth about $5 billion from May 2012 to April 2013, up 21 percent from the period a year earlier.

Source: Jaime Penaloza

Jaime Penaloza, a member of an Instagram group called "Sneakaholics," poses with his shoe collection.

What's more, the growth doesn't include all those "sneakerheads" buying and trading on their own. The craze right now is big enough to support its own convention, Sneaker Con, which kicks off Saturday in New York. Just like Comic Con, which brings together the nation's biggest comic book fanatics, this event gives sneaker connoisseurs a chance to buy, sell, and trade some of the most sought-after footwear on the market.

There also are websites like Kicksonfire.com, which was started by 24-year-old Furqan Khan as a blog in the mid-2000s to generate cash to help pay for college. The site tells readers which brands are releasing new models, and when and where to buy them. It's one of the sneaker-dedicated sites Durojaiye uses to get the latest buzz.

"The idea came about because there was no source for where you can find this information in one place," Khan said. "So me and one of my friends curated all this information from multiple sites and put it in one place that is easily accessible to people."

"Once we got traction, we became cool with the brands and they started sending the information directly to us," he said.

Kicksonfire now gets about 25 million page views a month, according to Quantcast, which measures Internet audiences.

Khan, who personally owns more than 1,000 pairs of sneakers, said a new designer sneaker comes to market about every other week. His site tracks the hottest pairs. Right now, according to Khan, the one to watch is Nike's Air Jordan 4 Retro, which is commonly called the Toro Bravo, which will be released on July 13.

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There's also the hyped released of the Reebok Shaqnosis, which is due to hit the shelves Friday, he said. Performer Chris Brown wore this style at the BET Awards a few weeks ago. The retail price is $125, but demand is expected to quickly drive up that figure.

"You would think that you are buying sneakers and wasting your money, but you realize really quickly that the kids are really smart and it is an investment, too. The prices really go up after the release date. You can trade them, too," said Khan.

And, it's not just teens and young adults driving sales. Jaime Penaloza, a member of an Instagram group called "Sneakaholics," doesn't fit the stereotypical profile of a sneaker fanatic. He's an accountant in his mid-30s and is married with children. Penaloza buys sneakers to wear and as an investment.

"My wife is OK with it," he said. "She knows that they are not a waste of money. She sees that I can make real cash if I turn around and sell my sneakers. I don't want to though. I have a good job. I don't need to do that."

Penaloza buys about 100 pairs sneakers a year and stores them in his home office, closet and garage. The self-proclaimed sneakerhead isn't sure how many he owns. But he has spent as much as $500 for a pair. That pair was the Nike Zoom Rookie Galaxy, which retailed for $215. After they quickly sold out, he bought them from a reseller on the day of the release.

There's chatter that the demand and price explosion could be contributing to a bubble. But, there's a case against it.

"As long as there is new innovative product there will be a market as there are new teenagers coming into the market every day," said Samuel Poser, managing director at Sterne Agee.

And, what's old can be new again. Reebook is selling a new version of the pump, which was first released in 1989, but you may not want to chuck your vintage Reebok pumps just yet. There's a previously worn men's pair from 1990—with a broken right pump—offered on eBay at $159. Start your bidding.

(CORRECTION: A previous version of this story incorrectly stated Furqan Khan considers to the Air Jordan 3 Retro '88 to be the hottest sneaker right now. It should have been Nike's Air Jordan 4 Retro "Toro Bravo," which will be released on July 13.)